Stereotactic Radiotherapy (SBRT) of Lung Metastasis

SBRT is an adaptation of the principles and experience gained from stereotactic brain RT. SBRT was developed in the early 90s at the Karolinska Institute in Stockholm, Sweden, and is used as an accepted alternative of treatment for patients with early stage lung cancer in many centers in Japan and a number of centers in Germany,USA and elsewhere. It is also now being used for patients who have lung metastases and extra-thoracic disease (primary or metastatic). Many reports indicate excellent local control (80-90% or higher) and minimal toxicity in well selected patients treated with thoracic SBRT.

SBRT has traditionally had the following features:

• High doses of radiation, usually in a few large fractions (it is "hypofractionated" compared with standard radiotherapy schedules)
• Multiple radiation beams coming from different directions in the same plane ('co-planar' beams) as well as from different directions and different planes relative to the patient's body ('non-coplanar' beams)
• Stereotactic beam placement, in that it is guided by a set of coordinates These coordinates are defined in relationship to the precise location of the tumor, determined from medical imaging (e.g. CT, MRI), rather than to a set of external marks (tattoos) or anatomical landmarks (such as bony structures)

Inclusion criteria

• Histological confirmation of malignancy, unless the risks of biopsy are unacceptable and the lesion has grown on serial CT scan and/or is PET positive.
• Eligible patients must have staging studies (e.g. chest radiograph, CT scan, MRI/CT Brain/Bone Scan) identifying them as:
• patients with stage I or II, non-metastatic NSCLC (T1, N0, M0; T2, N0, M0; or T3, N0, M0 chest wall primary tumors only)
• patients with a non-lung primary that is controlled and which has metastasized to the lungs alone, in whom potentially curative surgery would otherwise be an option (e.g. colorectal, breast, sarcoma…etc)
• the subset of patients with limited (low) volume metastatic NSCLC or other primary site tumors whom it is felt may derive benefit from highdose SBRT treatment to the primary or metastatic lung tumor. And in whom other sites of metastatic disease are being treated with the desire to achieve long term control. Lesions must meet size criteria in 4.1.2.1
• Patients who have potentially resectable disease should be considered medically inoperable, or else in the judgement of the thoracic surgeon and lung team, surgery is not considered the preferred management option
• Early stage lung cancer: ≤3 parenchymal lung lesions, Metastatic disease to lungs: ≤5 parenchymal lung lesions
• Patients with early stage primary NSCLC should have hilar or mediastinal lymph nodes that are considered N0 on clinico-radiological grounds (i.e. no clinico-radiological evidence of lymph node spread)
• In patients with early stage primary NSCLC and a co-existing malignancy, the co-existing malignancy must have an expected prognosis better than primary lung lesion
• Adequate lung function to tolerate the planned stereotactic radiation
• Previous conventional RT to mediastinum/lung allowed as long as SBRT is not expected to have a high probability of impairing lung function
• Must be ≥ 18 years of age
• Zubrod performance status must be between 0 and 3
• Women of child bearing potential and male participants must use an effective contraceptive method
• Willing and able to give informed consent

Exclusion criteria

• Patients with active systemic, pulmonary or pericardial infection
• No concurrent systemic therapy (chemotherapy, immunotherapy or biological therapy), apart from hormone therapy, is allowed
• History of active auto-immune diseases, including systemic lupus erythematous, rheumatoid arthritis, C.R.E.S.T., systemic sclerosis,scleroderma
• Potential candidate for concurrent chemo-radiation therapy
• Patient enrollment on other studies may be permissible. This will depend on patient and study characteristics.